Stripper



June 28, 1966 K. REHM 3,258,262

S TRI PPER Filed Aug. 28, 1964 5 Sheets-Sheet l INVENTOR Karl Rehm &My/1%( ATTORNEYS June 28, 1966 K. REHM 3,258,262

STRIPFER Filed Aug. 28, 1964 5 Sheets-Sheet 2 INVENTOR Kcrl Rehm w &

AT TOR N E' YS United States Patent O T 14 Claims. (ci. 271- 32 Thepresent invention relates to a Separator which for the purpose of thisspecification is understood to mean a device which, using an endlessconveying means, is adapted to withdraw from a pile conveyed articleswhich are flat or in the form of sheets, and to deliver them insuccession in a single row to a following conveying device. A conveyorbelt or conveyor drum may serve as the conveying means which effects thewithdrawal, and the entrainment force of the mentioned conveying meansmay be increased in known manner by suction.

It is known that in such separators, occasional separating faults whichlead to double or multiple withdrawals, can be not be entirely avoided.The reason for this lies, in particular, in diiferent characteristics ofthe articles conveyed, for example, different rigidity, thickness, coefiicient of friction, and possibly also porosity. This explains whydouble or multiple withdrawals occur relatively frequently, particularlyin separators for mail, because with these items, the dlferences areparticularly striking. Badly separated items of mail, however, lead todisturbances or misrouting in the following parts of a Sortinginstallation, for example, at switch points or in scanning devices.Etforts are therefore made to ensure or improve the separation of theitems of mail by means of separate additional devices.

For this purpose, so-called frictional stippers are known. These may,for example, comprise a pivotally mounted arm which is covered at itsfree end with a material having a high coeflicient of friction, forexample, polyvinyl chloride or rubber. The pivotal arm is biased againstthe conveying device which holds the items of mail, for example by meansof suction, and prevents by friction the excess items from advancing. Inorder to achieve this, the retaining force between the stripper and aletter engaged by it must, on the one hand, be greater than thefrictional force acting between two superimposed letters and, on theother hand, be less than the entrainment force which is effectivebetween the conveying device and a letter restirg directly .thereon.This condition is dflicult to fulfill in frictional strippers, however,and it is scarcely possible to maintain it for a long time with varieditems of mail. Furthermore, it is known in the case of drum separatorsto mount a suction member at a fixed distance from the drum. T hissuction member comprises a relatively large number of suction apertureson its active face adjacent to the items of mail. However, such a deviceno longer works satisfactorily when the thickness of the items of mailto be handled exceeds a certain value. Then, not only is the Consumptionof air high, but there is also the risk of thinner items being damaged.

In U.S. Patent No. 3,126,201, a device is disclosed for holding backdouble or multiple withdrawals on a separator of the kind heretoforementioned which device avoids the mentioned disadvantages. This isachieved by the use of one or more stripper members which areresiliently mounted, are continuously pressed by means of a relativelyWeak biasing force against the conveying side of the separating conveyordevice, and have one or more suction apertures on their active surfaceadjacent to the conveying device. The suction apertures are incommunication with a vacuum chamber through a suction pipe. Thesestripper members are constructed in the form of Shoe-like hollow bodiesof which each is Secured to a pivotally mounted arm.

The resiliently mounted suction strippers render it possible to fulllreliably the conditions which have to be fulfilled in such a device withregard to the relationship between retaining force, mutual frictionbetween the items of mail, and entrainment force, even when articles areconveyed which have unfavorable and very diflerent characteristics.

With these features of the prior art in mind, it is a main object of thepresent invention to provide stripper members which are considerablySimpler than those of the prior art.

It is another object of the invention to provide stripper members whichcan be made substantially lighter and which thus have less inertia thanprior art devices.

These objects and others ancillary thereto are accomplished according topreferred embodiments of the invention wherein there is provided adevice for holding back double or multiple withdrawals in associationwith a Separator of the kind described which device likewise usesmovable stripper members with suction apertures which are incommunication with a vacuum chamber through a suction pipe. As a furtherdevelopment of the means disclosed in the above-mentioned patent, itrelates to a particularly advantageous embodiment of the movable suctionstripper members. The feature of this device is that each strippermember forms a flexible tongue which is provided with at least onesuction aperture at its working surface facing the moving conveyingdevice and hearing against this in the position of rest, and whichitself acts as a suction line in that it has one or more cavities orpassages extending in the longitudinal direction.

In a further development, these stripper members are Secured, at the endwhich is remote from the conveying device and is in communication withthe vacuum chamber in such a manner that the connecting line between theSecured end and the suction apertures forms an angle of about 30 todegrees with the conveying direction. In conjunction with the strippermembers according to the invention, this feature provides specialelfects, explained below, which can not occur in the know frictionalstrippers.

In devices according to the invention, apart from their greaterSimplicity, the stripper members can, inter alia, be made considerablylighter and hence with a lower inertia than the above-mentioned vacuumstrippers constructed in the form of Shoe-like hollow bodies. Theconsequence of this is that the device remains fully effective even whenthe separating operation is carried out at high speed. Thus not only itsstatic but also its dynamic behavior is equal to or adaptable to all thecondtions which may occur in practice.

Additional objects and advantages of the present invention will becomeapparent upon consideration of the following description when taken inconjunction with the accompanying drawings in which:

FIGURE 1 is a schema tic plan View illustrating a portion of a Separatorconstructed in accordance with the present invention.

FIGURE 2 is a schematic plan view of a modified stripper member.

FIGURE 3 is a perspective View of one embodiment of a stripper memberwhich is rectangular in cross section, with a portion of one wallthereof shown raised to disclose further details.

FIGURE 4 is a perspective View similar to FIGURE 3 showing anotherembodiment.

FIGURE is a perspective view similar to FIGURES 3 and 4 showing afurther em'bodiment.

FIGURE 6 is a perspective view similar to FIGURES 3 to 5 showing stillanother embodiment.

FIGURE 7 is a perspective view of a stripper assembly in which thestripper members are circular in cross section.

FIGURE 8 is a perspective view of still another ernbodiment of astripper assembly.

With more particular reference to the drawings, FIG- URE 1 shows asuction conveyor -belt 2 which is guided around a driven pulley 1 and acounter pulley, not visible, and which is provided with, for example,two groups of holes 2'. The mutual spacing of the individual groups ofholes corresponds to the required conveying distance between theseparated items. The stack 3 of items to be separated rests in front ofa wall 4 with the items standing on edge. A suction trough 5 is mountedbehind the suction conveyor belt 2 in such a manner that, beginning inthe region of the front ends of the items in the stack 3, it extendsover a certain length in the direction of movement of the suctionconveyor belt. It is in communication, through a pipe socket 5', with asuction unit, not illustrated, the suction direction of which isindicated by the arrow 6. Mounted opposite the pulley 1 is a yieldablymounted roller 7, so that all the items of mail which travel towards theleft out of the range of action of the suction trough 5, are forciblygripped between the pulley 1 and roller 7 and delivered to a furtherconveying device, not illustrated.

As soon as a group of holes 2' in the moving suction conveyor belt 2coming from the right comes within range of the suction trough 5, theitems 8 in the stack 3 which is immediately adjacent to the 'belt 2 issucked against the belt by which it is conveyed in the direction of thearrow 9. The drawing illustrates the case where, apart from the item 8,two further items 8' and 8" are withdrawn from the stack and alsoconveyed in the direction of the arrow, which is undesirable. This may,for example, be caused by the fact that the items 8 and 8' are to someextent permea ble to air (porous) so that the negative pressure at thegroup` of holes 2' acts through these items and all of them are suckledtightly together and so are withdrawn jointly from the stack. Suchbehavior may be observed relatively frequently with post cards forexample. In order to hold back the multiple withdrawals occurring in theSeparator, such as the items 8' and 8" illustrated for example, thedevice according to the invention is used, which is described below.

The device comprises a plurality of stripper mem bers 10 which arearranged in succession in the conveying direction and each of whichfonms a flexible tongue which is provided with suction apertures 11 atits working face, that is, at its end face which faces the suctionconveyor belt 2. Each of these tongues comprises one or more longtudinalcavities or channels 12 which terminates, at the end remote from thesuction conveyor belt 2, in a vacuum chamber 13 which is incommunication through a suction socket 13' with a suction unit, thesuction direction of which is indicated by the arrow 14. At their endsnearer the vacuum chamber, the stripper members are Secured in such amanner that the connecting line between the point at which the strippermembers are fixed to the vacuum chamber elements and the end face formsnot too small an acute angle with the conveying direction of the belt 2.This angle preferably amounts to about 30 to 80 degrees, about 45degrees in the example illustrated. In their normal position, all thestripper members 10 bear with their suction apertures 11 against theconveyor .belt 2. The possible constructions of these stripper membersare discussed hereinafter with reference to examples of embodi ments.Their mode of operation will be explained first.

As soon as the item 8', entrained at high speed in the direction of thearrow 9 as a double withdrawal, comes within range of the retainingdevice, the first two of the tongue-like stripper members 10, as shownin FIGURE l, grip the item of mail 8' so firmly by suction that the item8' is separated from the item 8 bearing directly against the belt 2 inthe region of its movement past the end faces of the stripper memberscontaining the suction apertures 11. As a result, it becomes possiblefor the surrounding air to enter the space between the items 8' and 8 sothat the suction explained hereinbefore between the items 8' and 8quickly disappears and the item 8' is reliably held back. Only the item8 is then held by the group of holes 2' and conveyed by the suctionconveyor belt 2. As soon as the next group of holes 2' (not illustrated)comes within region of the suction trough 5 'as a result of the furthermovement of the belt 2, the item 8' is drawn aaginst the belt againstthe retaining force of stripper 10 and is entrained by the belt, whilethe item 8" now comes within reach of the stripper member by which it isheld back. As in all vacuum strippers, the negative pressures andsuction cross-sectional areas should be so dimensioned that theretaining force of the stripper members 10 is greater than thefrictional force between two items bearing against one another, but lessthan the force with which the items are entrained by the suctionconveyor belt 2.

The device according to the invention may also be used in acorresponding manner in connection with a Separator wherein a suctiondrum, for example, serves as an endless rotating conveying deviceinstead of a suction conveyor belt. It is likewise immaterial to themode of operation of this device whether the items -are conveyed on edgeor lying flat.

The tongue-like stripper members 10 are made from materials having anadequate coeicient of friction, such as PVC (polyvinyl chloride),Vulkollan (cross-linked polyurethane), rubber, or, in certaincircumstances, even leather. Their moment of resistance in the conveyingdirection is such that they can easily follow the suction force actingat their working surface. As a result, they can always bear reliablyagainst the oncoming item of mail, even if this is relatively thick, inwhich case the stripper member is at first thrust aside by the impact.

In order to obtain a smooth entry for the items, it is an advantage toprovide the stripper members 10 at their entry side with a covering of amaterial having a low coeficient of friction, or to mount in front ofthem a strip 15 of such a material, as seen in FIGURE 2.

The cross section of the stripper members 10, which are illustrated inthe device shown in FIGURE 1, is a rectangle of which one side,extending transversely to the conveying direction, is substantiallylonger than the other. For reasons of manufacture, it is advisable tomake each stripper member of two parts, the contact plane of whichextends in the longitudinal direction of the tongue formed thereby andparallel to the long side of the cross section. These two parts may berigidly connected by being stuck together, for example. It is anadvantage, however, for the two parts to remain unconnected, that is tosay, to bear loosely against one another.` As a result, the suctionapertures 11, and above al'l the passages or Channels 12 present in theinterier, can always be quickly and easily cleaned of adhering paper,dust and the like. The lateral sealing of the two loose parts isadequately ensured by the reduced pressure prevailing in the passages.

FIGURE 3 is a perspective view of the Construction of such a strippermember 10 comprising two loose parts 10a and 10b. Whereas the part 1011,which is shown in a partially raised position, is flat, that is to sayit is of equal thickness throughout, the part 101) is provided on theinside with lateral marginal strips 16. Similar intermediate strips 17form on the one hand the suction apertures 11 in the region of the endface of the stripper member 10 and, on the other hand, support the twoparts 10a and 10b in relation to one another so that the passages 12formed between them are retained against the action of the reducedpressure prevailing therein.

In order to counteract any unwanted stifiening of the stripper members,it is advisable to make provision for a satisfactory sliding capacity inthe plane of the contact between the two parts 10a and lOb. For thispurpose, both parts may simply be sprinkled with talcum. It is stillbetter to apply to at least one of the two parts at the contact surfacea sliding layer formed by a material which has a low coeflicent offriction, such as Teflon, for example. This layer should then be so thinthat it shows the same wear at the end face of the stripper member asthe material of the two parts 10a and 10b. It is further possible, andadvantageous, to produce one of the two flaplike parts 10a or lb-andpreferably the flat part 10aas a whole of a material having a lowcoefficient of friction, such as Teflon, for example.

Similar considerations apply to the modified embodiments of strippermembers which are illustrated in FIG- URES 4 to 6. There, below eachstripper member, which is partially folded back, a further strippermember is represented in the closed condition in each case.

Each of the stripper members 18 and 19 shown in FIG- URES 4 and 5'likewise comprises a flat part 18a or 19a and a second profiled part18b or 19b, respectively. This second part is provided in both caseswith lateral marginal strips 16 on the inside and with stud-like raisedportions 20 in the region of the end face of the tongue formed by thetwo parts. The cavity 12' formed between the two parts is maintained inthe stripper member 18 by a large number of spike-like members 21, whilestuds 22 of larger cross section are provided for this purpose in thestripper member 19.

In FIGURE 6, two stripper members 23 are shown as a furthermodification, each comprising two like parts 23:: and 2317. These partsare similar in construction to the part b of the stripper member 10(FIGURE 3). They differ from this only in the fact that the lateralmarginal strips 16' are provided with recesses 24 on the inside and thestrips 17' are provided with wedge-shaped incisions 25. In this manner areduction in the moment of resistance of this stripper is obtained inthe direction of the short side of the cross section.

In FIGURE 7, an embodiment of a device according to the invention isllustrated which comprises a large number of stripper members 26, eachof which is formed by an elongated hollow body of substantially circularcross section forming a flexible tube. These stripper members areparticularly simple to produce, but are not so easy to clean as thosedescribed previously.

In order to loosen up fiat items of mail to be separated, it is known touse jets of air which are blown ob'liquely against the leading edges ofthe items counter to the direction of conveying. This means can also beappled in conjunction with a device according to the present invention.One example of a device constructed in this manner is shown in FIGURE 8.A plate 13" for securing the device to the Separator i-s illustrated inthe housing 13 of the vacuum chamber. Here two groups of strippermembers 10, succeeding one another in the conveying direction, arearranged side by side (one above the order). A tube 27, which is incommunication with a blower or air compressor and which is provided withjet forming nozzles 28, extends between the two groups. A jet of airemergcs from each nozzle in a direction obliquely and in opposition tothe direction of conveying 9, as indicated by the arrow 29, whichfacilitates the -stripping process under certain conditions.

The embodiments of stripper members explained with reference to thedrawing are constructed in such a manner that the end face of the tongueacts as a working surface, this is to say the suction apertures are inthis end face. This is not a basic requirement, however. It would alsobe possible, within the scope of the invention, to arrange or constructthe tongue-like stripper members in such a manner that they bear againstthe conveying device with the end of the wide surface adjacent to theseparating conveying device, and that the suction apertures are in theportion of this surface.

It will be understood that the above description of the presentinvention is susceptible to various modifications, changes andadaptations, and the same are intended to be comprehended within themeaning and range of equivalents of the appended claims.

What is claimed is:

1. In a device for holding back double or multiple withdrawals in aSeparator for conveyed articles which are flat or in the form of sheetsand including an endless moving suction conveying means and at least onemovable stripper member having at its active surface fiacing theconveying means at least one suction aperture in communication with avacuum cha mber via .a suction line, with the retaining force exerted bythe stripper member being less than the entrainment force of theconveying means, the improvement wherein each stripper member is aflexible tongue having at least one suction aperture at its workingsurface facing the moving conveying means and hearing against theconveying means in its rest position, and at least one passage extendinglongituclinally through each tongue to define its own suction line.

2. A device for assuring that flat articles are separated from eachother, comprising, in combination:

endless conveying means for moving the shipments by exerting atransportin-g force thereon; and

at least one yieldable stripper means for exerting a retaining force onarticles which is less than the transporting 'force exerted by theconveying means on articles, the strip-per means having a suctionopening in a surface thereotf which faces the conveying means and saidsurface lying against the conveying means in the rest position of thestripper means, and the stripper means being in the form of a flexibletongue h-av ing a suction passage extending longitudinally therethroughfor placing the suction opening in communication with a vacuum pressurechamber.

3. A device as defined in claim 2, wherein each tongue is secured at theend which is remote from the conveying means and is in communicationwith the vacuum chamber in such a manner that the connecting linebetween the secured end and the suction openings forms an angle ofsubstantially 30 to degrees with the conveying direction.

4. A device as defined in claim 2, wherein there are a large number oftongues each of which is formed by an elongated hose-like hollow body ofsubstantially circular cross section.

5. A device as defined in claim 2, wherein the cross section of eachtongue is -a rectangle, of which one side extendin g transversely of theconveying direction is substantially longer than the other.

'6. A device as defined in claim 5, wherein each tongue is of two parts,the contact surfaces of which extend in the longitudinal direction ofthe tongue which they form and parallel to the long side of the crosssection.

7. A device as defined in claim 6, wherein at least one of the two partsis provided on the inside with lateral -marginal strips and with raisedportions which on the one hand form the suction openings in the regionof said surface and on the other hand support the two parts in relationto one another in such a manner that the passages formed between themare retained against the action of the negative pressure prevailingtherein.

8. A device as defined in claim 6, wherein the two parts of which thetongues are composed rest loosely one against the other.

9. A device as defined in claim 8, wherein at least one of the two partsis provided at the contact surface with a layer of a material having alow coefiicient of friction.

10. A device as defined in claim 8, wherein one of the two p arts has aflat shape and this part is of a material with a low coeflicient offriction.

11. A device as defined in claim 2 cornp'ising a layer of a materialhaving a -low coefficient of friction disposed at the side of the tonguefacing the arriving articles.

12. A device as defined in claim 2, wherein there are a plurality oftongues which are independent of one another and are arranged side byside in one row per-pendicul-ar to the conveying direction.

13. A dev-ice as de fined in claim 2, -Wheren there are a plurality oftongues which are independent of one another and which succeed oneanother in the conveying direction.

14. A device as defined in claim 13, wherein there are at least twogroups of tongues s uc ceeding one another in the conveying direction,and that at least one jet-forming nozzle is arranged in the gap betweenthese groups for directing a jet of air substantiaily in a directionopposite to the conveying direction.

References Cited by the Examner UNITED STATES PATENTS 3/1964 Rehm271--32 7/ 1965 B-uchwald 271--26 M. H ENSON WOOD, JR., Prmary Exwminer.

J. N. ERLICH, Assistant Examner.

1. IN A DEVICE FOR HOLDING BACK DOUBLE OR MULTIPLE WITHDRAWLS IN ASEPARATOR FOR CONVEYED ARTICLES WHICH ARE FLAT OR IN THE FORM OF SHEETSAND INCLUDING AN ENDLESS MOVING SUCTION CONVEYING MEANS AND AT LEAST ONEMOVABLE STRIPPER MEMBER HAVING AT ITS ACTIVE SURFACE FACING THECONVEYING MEANS AT LEAST ONE SUCTION APERTURE IN COMMUNICATION WITH AVACUUM CHAMBER VIA A SUCTION MEMBER WITH THE RETAINING FORCE EXERTED BYTHE STRIPPER MEMBER BEING LESS THAN THE ENTRAINMENT FORCE OF THECONVEYING MEANS, THE IMPROVEMENT WHEREIN EACH STRIPPER MEMBER IS AFLEXIBLE TONGUE HAVING AT LEAST ONE SUCTION APERTURE AT ITS WORKINGSURFACE FACING THE MOVING CONVEYING MEANS AND BEARING AGAINST THECONVEYOR MEANS IN ITS REST POSITION, AND AT LEAST ONE PASSAGE EXTENDINGLONGITUDINALLY THROUGH EACH TONGUE TO DEFINE ITS OWN SUCTION LINE.